The invention relates to solar converters and in particular to solar heating units for use in crop-drying systems. It should be noted, however, that the invention has also broader applications, for example in connection with the space heating of houses.
It is known to dry crops, such as harvested grain, in a variety of ways. The most common for small farms is to place the grain in a grain bin and to blow air into a duct located at the lower portion or false bottom of the bin. The passage of air through the bin tends to remove the moisture from the grain. This technique of drying grain is generally adequate without use of additional heat sources when the relative humidity is low. That is, at low humidity the ambient temperature is sufficient to perform the drying function. When the humidity is high, supplemental heat is added to the air flow in order to facilitate removal of moisture. Conventionally this addition of heat is carried out by fuel-burning heaters; however, it has also been proposed to use for this purpose, alternatively or additionally, solar heating units. These units may be housed in the bin or other structure itself, for example in the roof thereof, or they may be designed as free-standing units which are connected to the bin or the like by means of ducts.
Typically such solar heating units consist of an enclosure through which drying air is forced. Mounted in the enclosure is an absorber plate and the enclosure is covered by a transparent cover through which solar radiation is transmitted to the inside of the unit where it is absorbed, and converted into heat, by the absorber plate.